In this paper,the online measurement of the alkalinity of caustic washing liquid by the conductivity method was discussed,and a working curve of the conductivity vs.alkalinity was established,for which the correlation...In this paper,the online measurement of the alkalinity of caustic washing liquid by the conductivity method was discussed,and a working curve of the conductivity vs.alkalinity was established,for which the correlation coefficient is 0.9979(n=7).The influence of the temperature of the caustic washing liquid and the presence of coexisting ions,such as iron and oil,on the accuracy of the conductivity method was discussed.The temperature is compensated for by establishing the correlation between conductivity and temperature.When the iron concentration is≤1000 mg/L,and the oil concentration is≤1000 mg/L,the deviation in the results obtained using the conductivity and titration methods is≤2.5 g/L.The t-test results show that there is no systematic devia-tion between the conductivity and titration methods.The conductivity method has the advantages of a fast response and good real-time performance,which meet the requirements for the online determination of the alkalinity of caustic washing liquid.展开更多
In this study the potential of sunflower meal ethanol-wash powder(SEWP)to be used as antimicrobial agent in liquid foods was investigated.SEWP represents the waste of the main process of protein isolation from industr...In this study the potential of sunflower meal ethanol-wash powder(SEWP)to be used as antimicrobial agent in liquid foods was investigated.SEWP represents the waste of the main process of protein isolation from industrially produced sunflower meal.The washing liquids remaining after treatment of the sunflower meal with 75%aqueous ethanol solution were collected and turned into powder rich in bioactive compounds.Due to its recognized properties,different concentrations(2.5 and 5%w/v)of SEWP were first tested in vitro against Alicyclobacillus acidoterrestris and a cocktail of Pseudomonas putida and Pseudomonas fluorescens strains,using appropriate culture media.Then,the SEWP antimicrobial efficacy was tested on two real food matrices differing in their composition.Soymilk,rich in proteins,and apple juice,composed mainly of carbohydrates,were used as food models.Concentrations equal to 1%,1.5%,2%,2.5%,5%and 7.5%(w/v)SEWP were tested in the juice,whereas the sole three highest concentrations were tested in the soymilk.Both beverages were pre-inoculated with different spoilage bacteria.The same mix of Pseudomonas spp.and A.acidoterrestris strain used for the in vitro test were employed to contaminate the soymilk and the apple juice,respectively.In vitro results showed moderate effects of SEWP against selected target microorganisms.On the contrary,two completely different microbial evolutions were recorded in the soymilk and apple juice.The three concentrations of SEWP were slightly effective against spoilage of soymilk,whereas all the concentrations used in the juice were sufficient to completely inhibit microbial growth of A.acidoterrestris.The shelf life of the apple juice supplemented with 1%SEWP was extended for more than 21 days.Considering both the antimicrobial efficacy and the sensory properties of the juice,the lowest SEWP concentration(1%w/v)demonstrated the best result as a bioprotectant.Overall results imply dependence of SEWP antimicrobial efficiency on food composition and a need of preliminary evaluation of the product if used as an antimicrobial agent in the food industry.展开更多
文摘In this paper,the online measurement of the alkalinity of caustic washing liquid by the conductivity method was discussed,and a working curve of the conductivity vs.alkalinity was established,for which the correlation coefficient is 0.9979(n=7).The influence of the temperature of the caustic washing liquid and the presence of coexisting ions,such as iron and oil,on the accuracy of the conductivity method was discussed.The temperature is compensated for by establishing the correlation between conductivity and temperature.When the iron concentration is≤1000 mg/L,and the oil concentration is≤1000 mg/L,the deviation in the results obtained using the conductivity and titration methods is≤2.5 g/L.The t-test results show that there is no systematic devia-tion between the conductivity and titration methods.The conductivity method has the advantages of a fast response and good real-time performance,which meet the requirements for the online determination of the alkalinity of caustic washing liquid.
基金supported by the Bulgarian National Science Fund,project No.KП-06-H37/21.
文摘In this study the potential of sunflower meal ethanol-wash powder(SEWP)to be used as antimicrobial agent in liquid foods was investigated.SEWP represents the waste of the main process of protein isolation from industrially produced sunflower meal.The washing liquids remaining after treatment of the sunflower meal with 75%aqueous ethanol solution were collected and turned into powder rich in bioactive compounds.Due to its recognized properties,different concentrations(2.5 and 5%w/v)of SEWP were first tested in vitro against Alicyclobacillus acidoterrestris and a cocktail of Pseudomonas putida and Pseudomonas fluorescens strains,using appropriate culture media.Then,the SEWP antimicrobial efficacy was tested on two real food matrices differing in their composition.Soymilk,rich in proteins,and apple juice,composed mainly of carbohydrates,were used as food models.Concentrations equal to 1%,1.5%,2%,2.5%,5%and 7.5%(w/v)SEWP were tested in the juice,whereas the sole three highest concentrations were tested in the soymilk.Both beverages were pre-inoculated with different spoilage bacteria.The same mix of Pseudomonas spp.and A.acidoterrestris strain used for the in vitro test were employed to contaminate the soymilk and the apple juice,respectively.In vitro results showed moderate effects of SEWP against selected target microorganisms.On the contrary,two completely different microbial evolutions were recorded in the soymilk and apple juice.The three concentrations of SEWP were slightly effective against spoilage of soymilk,whereas all the concentrations used in the juice were sufficient to completely inhibit microbial growth of A.acidoterrestris.The shelf life of the apple juice supplemented with 1%SEWP was extended for more than 21 days.Considering both the antimicrobial efficacy and the sensory properties of the juice,the lowest SEWP concentration(1%w/v)demonstrated the best result as a bioprotectant.Overall results imply dependence of SEWP antimicrobial efficiency on food composition and a need of preliminary evaluation of the product if used as an antimicrobial agent in the food industry.
